Receive 10% discount storewide + entry in the monthly draw to win a AU$150 shopping voucher.  Join the Boulder Opal Club here.
Buying an Opal Gemstone

Buying an Opal Gemstone

Posted by Therese Evert on 4th Nov 2021

If you love opal and would like to get one to set into jewellery here’s a few things you should consider before you make the decision to buy.

    1. Is the opal solid?

A solid opal is a natural gemstone that has been cut and polished to expose the colour and prepare the opal gemstone for setting. Nothing has been added and the gemstone is natural. A solid opal can be worn in water and is the best form of opal for investment.

Opal gemstones can also come in the form of doublets and triplets.

Doublets and triplets are man-made composites in which a thin slice of opal is glued to a backing. In the case of triplets, the opal is very thin and encased in a quartz cap. Doublets are weak on the edges and chip easy. Triplets can be damaged if immersed in water.

A solid opal can withstand normal wear and can be worn in water.

Image from

2. What type of opal are you looking for?

There are three generic types of opal.

Boulder Opal is found near and around the small central Western Queensland towns of Winton and Quilpie. The defining feature of boulder opal is rock. Boulder opal is opal that has been formed in and bonded to rock. Boulder opal presents as colourful and scenic.

White Opal is found near and around the small township of Coober Pedy in South Australia. White opal is found in pockets in the clay beds and is precious opal (opal with complex colour) hosted by white common opal (opal with little colour). White opal is generally soft pink and green in colour.

Black Opal is found near and around the township of Lightning Ridge in New South Wales. Black opal is found in pockets in the clay bed and presents as “nobbies” – small chucks of black/grey common opal containing bands of precious (colourful) opal. Black opal is generally red, green, and blue and typically dark in colour.

Once you’ve established the opal is a solid opal decide on which type you like.

3. Study the opal up close.

Now that you’ve found your opal put it under the light and look for cracks, crazing and pits. Cracks, crazing, and pits are inclusions that undermine the value of an opal. Fluorescent light is better than direct sunlight for finding inclusions and the use of a jeweller’s loupe (magnifier) can be helpful. Digital photography is also another way to really see inside the opal.

4. Understanding value.

An opal is priced on its richness and clarity of colour, complexity of pattern, size/weight, and demand. Some colours are rarer than others e.g., red is a very rare colour in opal, so if a gemstone has red in it the value will go up. Opal can be valued on carat weight or piece price.

5. Opal is jewellery design.

Boulder opal is generally cut in free form shapes which allow for creativity in jewellery design. Furthermore, boulder opals are usually cut flat (the opal face is flat rather than cabochon) as the veins are often very thin. Both the former (free form shape) and latter (flat opal face) make boulder opals especially suitable to setting in a bezel. A bezel setting (as opposed to a claw setting) is a great way to set a large stone and gives added protection to the opal through a raised ridge around the gemstone.

Black and white opals are traditionally cut with a cabochon and are often set in claws. This is an elegant way to set an opal but does not wear as well as a bezel setting. In other words a claw setting is more suitable for dress wear rather than everyday wear.

Bezel setting

Claw setting

Size matters …

The size of the opal will determine how much the “make” will cost. When using precious metals such as yellow gold, white gold and silver consider that more metal will be used in setting larger gemstones.

Buying an unset opal and having it set into a unique piece of jewellery is a great way to express your individuality.

Read more about buying opal here: